Vessels suitable for transportation on trailers are typically provided with one or more drain openings, usually in the transom, at a location below the water line. When the vessel is on the water, its drain openings are closed by plugs, which are typically threaded into the drain openings. When the vessel is removed from the water for transportation on a trailer, the plugs are removed to discharge water accumulated in the hull during use of the vessel, and also to discharge rainwater.
An all too common problem is that, when a vessel is launched from a trailer, the replacement of the drain plug or plugs is overlooked, and the vessel fills with water and sinks. Based on recent insurance studies, it has been determined that, in about 12 percent of cases in which a boat sank while underway, the cause was a missing drain plug, and that the average cost of repairing a boat that has been underwater, even briefly, is around 40 percent of the total value of the boat.
Because of the potentially serious consequences of failure to install drain plugs when launching a vessel, it is desirable to provide a reliable means to remind the boater of the need to install drain plugs before launch. Various approaches addressing the problem have been proposed.
One example is the electrical drain plug warning system described in U.S. Pat. No. 5,966,080, granted Oct. 12, 1999 to Bigsby. The Bigsby warning system utilizes a magnet in the plug and a magnetic sensor in associated with the plug-receiving aperture. The sensor is wired to activate an alarm when the user operates a key switch if the plug is not present in the plug-receiving aperture.
Another example is the drain plug retention system described in U.S. Pat. No. 7,316,195, granted Jan. 8, 2008 to DeHart. In the DeHart drain plug retention system, a drain plug wrench and a flotation device are attached to a key chain. Either the wrench or the flotation device has a plug-retaining feature. Because the key chain is also associated with the boat's ignition key, the boater is reminded to install the plug before operating the boat.
In a third example, described in U.S. Pat. No. 4,516,515, granted on May 14, 1985 to Johnson, a plug retainer, into which a drain plug can be threaded, is secured by mounting screws to the transom of a boat. A tie-down strap for securing the boat to a trailer is connected to a flag which is held in the retainer by the drain plug when the drain plug is threaded into the retainer. To remove the boat from the trailer, it is necessary to release the flag from the plug retainer by rotating the plug. When the boater rotates the plug to release the flag, he is reminded to install the plug in its drain opening.
A need exists for a simple, reliable, and versatile drain plug reminder that does not require permanent attachment of a plug retainer or similar element to the boat hull.